The present invention relates to a ball bushing comprising a sleeve, a cage and a number of closed ball paths with balls guided by the cage, the balls being loaded between the sleeve and a shaft surrounded by the sleeve in a portion of each ball path, the ball paths having curved portions on each side of the loaded portions.
Such a ball bushing is previously known, for example, by the German published application, No. 2,333,336. Such ball bushings have advantageous properties, such as that they consist of only few separate parts, which simplifies manufacture and assembly, which in its turn makes it possible to provide inexpensive bushings. One important factor for obtaining a bushing with only few parts is that the outer sleeve is made of only one part, i.e., that no separate raceways for the loaded balls are provided in the sleeve. The whole sleeve must therefore be made of a material which is suitable for being provided with integral ball paths, i.e., preferably steel. This means, however, that the sleeve is comparatively difficult to work compared to a sleeve of, for example, in the shape of steel bars, which is a disadvantage, because it means that the bushing comprises more parts, and that the shape of the plastic sleeve will be comparatively complicated.
The manufacture of a sleeve such as the one shown in the above mentioned publication calls for several working operations, such as turning of grooves in the envelope surface and at the ends of the bore, the provision of a hexagonal bore, the provision of special cut-outs at the curved portions of the ball paths.